Lighting concern

Can someone look at my calculations to see if I'm in line.

Thank you

Core lighting (285 fixtures) Levels A/B/C/D/E

Given: 120 Watts (lamp 100 watt hps + Ballast 20 watt) x 285 lamps (interior zone) = 34,200 Watts or 34.2 Kw

So, 34.2 kw x 0.07 per kwh (average electrical cost) = $2.394 per hour.

Then: $2.394 X 24hrs = $57.456 per day.

Then: $57.456 X 365 = $20,971.44 per year to operate.

Level F (6 fixtures)

Given: 270 Watts (lamp 250 watt hps + Ballast 20 watt) x 6 lamps (upper ramp zone) = 1,620 Watts or 1.62 Kw

So, 1.62 kw x 0.07 per kwh (average electrical cost) = $.1134 per hour.

Then: $.1134 X 24hrs = $2.72 per day.

Then: $2.72 X 365 = $993.38 per year to operate

Core Lighting Reduction (171 fixtures)

If were able to shut down four of the six zones: 171 units

120 Watts (lamp 100 watt hps + Ballast 20 watt) x 171 lamps (interior zone) = 20,520 Watts or 20.52 Kw

So, 20.52 kw x 0.07 per kwh (average electrical cost) = $1.4364 per hour.

Then: $1.4364 X 24hrs = $34.4736 per day.

Then: $34.4746 X 365 = $12,582.86 per year to operate.

Monday through Friday: Off = 8:00 pm until 8:00 am = 60 hours X 52 = 3,120

Saturday and Sunday = off = 48 hours X 52 = 2,496

Holidays (5) = 60 hours (based off of 12 hour regular shut off)

Totals off hours = 5,676 hours X $1.4364 (average electrical cost) = $8,153.00 savings per year

Other options still evaluating:

LEDs are a very inefficient light source, while HPS is the most efficient known. LEDs are less than half the efficiency. Long life though so low maintenance. But practical LEDs to replace 100W HPS are way too expensive.

The way to save energy is to turn the fittings off. Unfortunately HPS do not turn off and on very well. The solution is to use fluorescent instead, preferably dimming 35watt T5 (which are as efficient as HPS). These can be dimmed to avoid over illumination (a problem with car parks as you must assume a low maintenance factor of about 0.5) and turned off when the space is unoccupied (via motion sensor).